Hair bleaching is a well-known process in the hair cosmetic field. Hair bleaching involves the application of an oxidizing agent to the hair for a period of time effective to achieve a desired lighter hair shade. The oxidizing agent typically is a hydrogen peroxide solution in concentrations ranging from 6 to 12% by weight. The hydrogen peroxide is applied to the hair under alkaline pH conditions and gradually lightens the shade of the hair by oxidizing the melanin that gives it color.
To enhance the lightening efficacy of the peroxide solution, a persulfate salt-based formulation may be incorporated as a “booster”. The sodium, potassium or ammonium persulfate salt is provided as a powder, which is mixed with the hydrogen peroxide solution prior to use. The mixed product is then applied to the hair for a period of time effective to achieve the desired lighter hair shade.
Currently, hair bleaches are most commonly found in the two-component kit form. One component comprises an aqueous-based hydrogen peroxide composition containing solution or emulsion. The second component comprises a powdered bleach composition that contains persulfate salts and alkaline agent(s), which act as accelerators of the bleaching process when the two components are combined. This powdered bleach composition may be used alone to bleach hair or in combination with an aqueous hydrogen peroxide composition. The hydrogen peroxide and persulfates are very reactive when combined and form nascent oxygen in addition to hydrogen and sodium sulfide. The nascent oxygen greatly facilitates oxidizing and bleaching of melanin from the hair.
The salts and other active ingredients (such as alkaline agents) routinely originate as a powdery mixture of ingredients which are then transformed into a paste by mixing with water or other liquid. The powdery mixture often has the disadvantage of dusting. The oxidizing and alkaline agents in the powdery mixture may be harmful if ingested or inhaled; therefore, it is desirable to obtain a hair bleach that does not cause this dusting.
De-dusted formulations have been developed to control or reduce the dusting in powdered bleaching compositions. The de-dusted formulation generally mixes the powder with at least a basic oil, such as mineral oil or ethyldexyl pelargonate, resulting in a cream-type formulation. Typically, these prior art chemical systems are either unstable (causing separation of the oil and the salt phases) or too waxy and, therefore, cosmetically un-appealing after premature formula separation due to the presence of oils and salts. The separation has the effect that different portions of the same batch of powder taken from different locations in the batch have different chemical compositions and thus may provide a different bleaching effect.
There is a desire and a long-standing need to overcome these disadvantages of the current technology with regards to controlled hair bleaching with a cream formulation. The primary challenge in developing a cream bleach resides in the need to develop a formulation that contains the necessary salt concentration level within a small oil matrix, which remains consistent enough to be cosmetically appealing and desirable to hair and scalp application with minimum damage, and has almost no physical separation of the components.